function HANNING_WIN = my_hanning_win(win_len)
i=1;HANNING_WIN=zeros(1,win_len);
while i<=win_len
    HANNING_WIN(i)=0.5*(1-cos(2*pi*i/(win_len-1)));
    i=i+1;
end
amp=win_len/sum(HANNING_WIN);
HANNING_WIN=HANNING_WIN*amp;
end